1. Field of the Invention
This invention relates to an image formation apparatus, such as an electronic copying machine, provided with a selective sheet sorting function.
2. Description of the Prior Art
Known electronic copying machines of a known construction include a copying device, an automatic original feeder and a sorting device.
The sorter device includes a vertically movable support frame, a plurality of trays stacked vertically along the support frame, and a pair of feed rollers which transport sheet material discharged by the copying device via a pair of discharge rollers to a selected one of trays. A sorter device of this type is disclosed in U.S. Pat. Nos. 3,879,032 and 4,618,245.
In the sorter device of the above known arrangement, the sorting capacity depends on the number of trays and the space between adjacent trays. The number of trays decides the number of copies that can be sorted. For example, if the sorting device has twenty trays, operators must use the copying device for sorting no more than twenty copies. The space between adjacent trays decides the number of original documents to the copied in the sorting mode. This is because, in the sorting mode, copied papers are discharged onto each tray of the stacked trays. For example, if the space between adjacent trays corresponds to twenty papers, twenty-one to forty original documents must be copied in two separate copying operations.
Prior art sorting devices thus fail to satisfy the various demands for sorting.